ENH: Coulomb: new particle electric force model calculating Coulomb forces

Problem

OpenFOAM lacked a Lagrangian model for electrostatic forces acting on particles based on their diameters.

Solution

The present commits furnish a model of this kind, along with essential underlying changes in the 'electricPotential' function object for evaluating the electric field. The coupling is one way (for now).

Meta-data

• EP1880
• linux64ClangDPInt32Opt (clang13)
• linux64GccDPInt32Opt
• linux64GccSPDPInt64Debug
• Alltest: No new error/No change in existing output
• No output change in all operating conditions except the following:
  • The electric field is computed according to the new Boolean input electricField instead of writeDerivedFields toogle.